The finds were made by a five-year-old boy and his friend.Pictured here: Stone Age artefacts discovered in Sotkamo. Kainuu Museum says the lighter object may be a sharpening stone, while the darker one is a four-sided stone axe that likely once had a handle. Image: Kainuun Museo Yle News13:22Kainuu Museum has added two new prehistoric artefacts to its collection following a shoreline discovery by two young children.One of the items appears to be a sharpening stone, the other the blade of a four-sided stone axe.A five-year-old boy and his friend found the tools when playing along a shoreline exposed by low water levels.The mother of one of the children alerted Kainuu Museum after taking a closer look at the stones the kids had collected.Jouni Väänänen, an archaeologist at the museum, said the discovery is rare.For now, the artefacts are being stored at Kainuu Museum, where they will be displayed in a glass case over the summer. In the autumn, the plan is to transfer them to the Finnish Heritage Agency.Lake water levels across much of Finland have been exceptionally low this spring.